GSSManager (GNU Classpath 0.94-pre Documentation)

The GSSManager class is an abstract class that serves as a factory for three GSS interfaces: {@link GSSName}, {@link GSSCredential}, and {@link GSSContext}. It also provides methods for applications to determine what mechanisms are available from the GSS implementation and what nametypes these mechanisms support. An instance of the default GSSManager subclass may be obtained through the static method {@link #getInstance()}, but applications are free to instantiate other subclasses of GSSManager.

All but one method in this class are declared abstract. This means that subclasses have to provide the complete implementation for those methods. The only exception to this is the static method {@link #getInstance()} which will have platform specific code to return an instance of the default subclass.

Platform providers of GSS are required not to add any constructors to this class, private, public, or protected. This will ensure that all subclasses invoke only the default constructor provided to the base class by the compiler.

A subclass extending the GSSManager abstract class may be implemented as a modular provider based layer that utilizes some well known service provider specification. The GSSManager API provides the application with methods to set provider preferences on such an implementation. These methods also allow the implementation to throw a well-defined exception in case provider based configuration is not supported. Applications that expect to be portable should be aware of this and recover cleanly by catching the exception.

It is envisioned that there will be three most common ways in which providers will be used:

The application does not care about what provider is used (the default case).
The application wants a particular provider to be used preferentially, either for a particular mechanism or all the time, irrespective of mechanism.
The application wants to use the locally configured providers as far as possible but if support is missing for one or more mechanisms then it wants to fall back on its own provider.

The GSSManager class has two methods that enable these modes of usage: {@link #addProviderAtFront(java.security.Provider,org.ietf.jgss.Oid)} and {@link #addProviderAtEnd(java.security.Provider,org.ietf.jgss.Oid)}. These methods have the effect of creating an ordered list of (provider, oid) pairs where each pair indicates a preference of provider for a given oid.

The use of these methods does not require any knowledge of whatever service provider specification the GSSManager subclass follows. It is hoped that these methods will serve the needs of most applications. Additional methods may be added to an extended GSSManager that could be part of a service provider specification that is standardized later.

Example Code

GSSManager mgr = GSSManager.getInstance();

// What mechs are available to us?
Oid[] supportedMechs = mgr.getMechs();

// Set a preference for the provider to be used when support is needed
// for the mechanisms "1.2.840.113554.1.2.2" and "1.3.6.1.5.5.1.1".

Oid krb = new Oid("1.2.840.113554.1.2.2");
Oid spkm1 = new Oid("1.3.6.1.5.5.1.1");

Provider p = (Provider) (new com.foo.security.Provider());

mgr.addProviderAtFront(p, krb);
mgr.addProviderAtFront(p, spkm1);

// What name types does this spkm implementation support?
Oid[] nameTypes = mgr.getNamesForMech(spkm1);

Constructor Summary
	GSSManager()

Method Summary
abstract void	addProviderAtEnd(Provider p, Oid mech) This method is used to indicate to the GSSManager that the application would like a particular provider to be used if no other provider can be found that supports the given mechanism.
abstract void	addProviderAtFront(Provider p, Oid mech) This method is used to indicate to the GSSManager that the application would like a particular provider to be used ahead of all others when support is desired for the given mechanism.
abstract GSSContext	createContext(byte[] interProcessToken) Factory method for creating a previously exported context.
abstract GSSContext	createContext(GSSCredential myCred) Factory method for creating a context on the acceptor' side.
abstract GSSContext	createContext(GSSName peer, Oid mech, GSSCredential myCred, int lifetime) Factory method for creating a context on the initiator's side.
abstract GSSCredential	createCredential(int usage) Factory method for acquiring default credentials.
abstract GSSCredential	createCredential(GSSName aName, int lifetime, Oid mech, int usage) Factory method for acquiring a single mechanism credential.
abstract GSSCredential	createCredential(GSSName aName, int lifetime, Oid[] mechs, int usage) Factory method for acquiring credentials over a set of mechanisms.
abstract GSSName	createName(byte[] name, Oid nameType) Factory method to convert a contiguous byte array containing a name from the specified namespace to a {@link GSSName} object.
abstract GSSName	createName(byte[] name, Oid nameType, Oid mech) Factory method to convert a contiguous byte array containing a name from the specified namespace to a GSSName object that is an MN.
abstract GSSName	createName(String nameStr, Oid nameType) Factory method to convert a contiguous string name from the specified namespace to a {@link GSSName} object.
abstract GSSName	createName(String nameStr, Oid nameType, Oid mech) Factory method to convert a contiguous string name from the specified namespace to an GSSName object that is a mechanism name (MN).
static GSSManager	getInstance() Returns the default GSSManager implementation.
abstract Oid[]	getMechs() Returns an array of {@link Oid} objects indicating mechanisms available to GSS-API callers.
abstract Oid[]	getMechsForName(Oid name) Returns an array of {@link Oid} objects corresponding to the mechanisms that support the specific name type.
abstract Oid[]	getNamesForMech(Oid mechanism) Returns name type Oid's supported by the specified mechanism.

This method is used to indicate to the GSSManager that the application would like a particular provider to be used if no other provider can be found that supports the given mechanism. When a value of null is used instead of an Oid for the mechanism, the GSSManager must use the indicated provider for any mechanism.

Calling this method repeatedly preserves the older settings but raises them above newer ones in preference thus forming an ordered list of providers and Oid pairs that grows at the bottom. Thus the older provider settings will be utilized first before this one is.

If there are any previously existing preferences that conflict with the preference being set here, then the GSSManager should ignore this request.

If the GSSManager implementation does not support an SPI with a pluggable provider architecture it should throw a GSSException with the status code {@link GSSException#UNAVAILABLE} to indicate that the operation is unavailable.

Parameters: p The provider instance that should be used whenever support is needed for mech. mech The mechanism for which the provider is being set.

Throws: GSSException If this service is unavailable.

addProviderAtFront

This method is used to indicate to the GSSManager that the application would like a particular provider to be used ahead of all others when support is desired for the given mechanism. When a value of null is used instead of an Oid for the mechanism, the GSSManager must use the indicated provider ahead of all others no matter what the mechanism is. Only when the indicated provider does not support the needed mechanism should the GSSManager move on to a different provider.

Calling this method repeatedly preserves the older settings but lowers them in preference thus forming an ordered list of provider and Oid pairs that grows at the top.

Calling addProviderAtFront with a null Oid will remove all previous preferences that were set for this provider in the GSSManager instance. Calling addProviderAtFront with a non-null Oid will remove any previous preference that was set using this mechanism and this provider together.

Parameters: p The provider instance that should be used whenever support is needed for mech. mech The mechanism for which the provider is being set.

Throws: GSSException If this service is unavailable.

createContext

Factory method for creating a context on the initiator's side. Context flags may be modified through the mutator methods prior to calling {@link GSSContext#initSecContext(java.io.InputStream,java.io.OutputStream)}.

Parameters: peer Name of the target peer. mech Oid of the desired mechanism. Use null to request default mechanism. myCred Credentials of the initiator. Use null default initiator principal. lifetime The request lifetime, in seconds, for the context. Use {@link GSSContext#INDEFINITE_LIFETIME} and {@link GSSContext#DEFAULT_LIFETIME} to request indefinite or default context lifetime.

Returns: The context.